函数逼近与曲线拟合，包含梯形公式、Simpson公式、Romberg公式。-Function approximation and curve fitting, including trapezoidal, Simpson formula, Romberg formula.

提供级数法和Lanczos逼近法计算伽马函数近似值，java语言编写-Provide progression method and Lanczos approximation to calculate the gamma function approximation, java language